1. Field of the Invention
The present invention relates to an optical apparatus such as an interchangeable lens or a camera in which the deterioration of image stabilizing drive characteristics caused by changes in the temperature at the time of shooting, or by deterioration with time, is reduced.
2. Description of the Related Art
In current cameras, since all of the operations that are important in shooting such as determination of exposure and focusing are performed automatically, the possibility of failure in shooting is very low, even if the photographer is not skilled in camera operation. In recent years, since systems that reduce image blur caused by camera shake have been developed, the factors that can lead photographers to a failure in shooting have been eliminated almost completely.
Camera shake when shooting generally has frequencies in the range of 1 to 12 Hz. In some cameras, taking of a photograph free from image blur is enabled even if such camera shake occurs at the time of depressing the shutter release button. To do this, it is necessary to accurately detect vibration of the camera in terms of acceleration and velocity caused by the hand shaking. Based on the result of the detection, changes in the optical axis caused by vibration of the camera are cancelled optically or electronically for image stabilization.
Japanese Patent Application Laid-Open No. H10-319465 discloses a lens shift apparatus in which a movable frame is guided by rotation of balls, and rotation of the movable member about an optical axis is prevented by springs. To reduce drive resistance, at least three balls are held between a fixed member and the movable member by means of the springs. Thus, play of the guide portion in the optical axis direction is eliminated by a simple structure.
In the structure in which a movable shift portion is supported on a fixed member by means of an elastic support member such as a spring as is the case with the structure disclosed in Japanese Patent Application Laid-Open No. H10-319465, resonance or oscillation is caused by hand shake or vibration of the camera due to the presence of the natural frequency of the spring. If this occurs and the movable shift portion oscillates greatly, there is a risk that the movable shift portion may collide with a portion that mechanically regulates the movable range of the shift motion and image stabilizing drive characteristics may be deteriorated.